Alfredo has been contributed to Apache Hadoop and it is available as part of Hadoop 1.0.x and Hadoop 0.23.x releases.
For details please refer to the Apache Hadoop site.
Alfredo is also available in Cloudera's Distribution Including Apache Hadoop CDH3.
Alfredo is a Java library consisting of a client and a server components to enable Kerberos SPNEGO authentication for HTTP.
Alfredo also supports additional authentication mechanisms on the client and the server side via 2 simple interfaces.
Alfredo is distributed under Apache License 2.0.
Alfredo forces authentication on protected resources, once authentiation has been established it sets a signed HTTP Cookie that contains an authentication token with the user name, user principal, authentication type and expiration time.
Subsequent HTTP client requests presenting the signed HTTP Cookie have access to the protected resources until the authentication token expires.